1. Field of the Invention
The present invention relates to a magnetic tape tension control device in a tape running system of a video tape recorder (VTR) or the like.
2. Description of the Prior Art
In the case of an apparatus which draws out a magnetic tape (hereinafter referred to as a tape) from a supply reel for recording and reproducing signals, such as In the VTR, it is necessary to keep constant the tension of the drawn-out tape constant in order to stably magnetically record and reproduce signals while maintaining a constant contact state between the tape and the magnetic head. Keeping the tape tension constant is also necessary from the viewpoint of decreasing damage of the tape.
In order to stabilize the tape tension, hitherto, it has been attempted to detect the tension of the drawn-out tape, feed the detected tension, and control the torque of a first motor for directly driving the supply reel on which the tape is wound, thereby stabilizing the tension of the tape (for example. See "Collection of Technical Papers of Modern VTR Design Technologies," edited by the Japan Industrial Technology Center).
In such a conventional configuration, there is a limit in enhancing the response of the feedback system Including the first motor to cause the supply reel to follow the motion of the takeup reel or the capstan responsible for speed control of the tape. In particular, If the response of the capstan or the takeup reel to a tape speed command is increased in order to improve controllability, the tape becomes too tense or too loose.